#include<stdio.h>
 
int myCal(int n1, int n2, char oper) {
 
	//定义一个变量 res ,保存运算的结果
	double res = 0.0;
 
	switch(oper) {
	case '+' :
		res = n1 + n2;
		break;
	case '-':
		res = n1 - n2;
		break;
	case '*':
		res = n1 * n2;
		break;
	case '/':
		res = n1 / n2;
		break;
	default :
		printf("你的运算符有误~");
	}
	printf("\n%d %c %d = %.2f\n", n1, oper, n2, res);
	return res;
 
}
 
void sayHello() {
	printf("你好，世界");
}